FACTBOX-Update on U.S. NTSB investigation of 787 fire in Boston

January 24, 2013|Reuters

WASHINGTON, Jan 24 (Reuters) - The U.S. NationalTransportation Safety Board on Thursday released moreinformation about its investigation into a battery fire on aparked Boeing Co 787 Dreamliner at Boston airport on Jan.7, and a separate battery failure that forced another 787 tomake an emergency landing in Japan.

Following is a list of some key preliminary findings andfacts announced by NTSB Chairman Deborah Hersman:

BATTERY AND ASSOCIATED SYSTEMS:

- The lithium-ion battery involved in both incidents wasmade by the Japanese company, GS Yuasa. The company isassisting with both the U.S. and Japanese investigations intothe separate events.

- Investigators found evidence in the battery of fire,short-circuits and "thermal runaway," a chemical reaction inwhich an increase in temperature changes the conditions andincreases the temperatures further.

- It remains unclear in what sequence those events occurred,or how they were triggered, according to the NTSB.

- Investigators also reported structural and componentdamage in a 20-inch radius around the battery, which powered theauxiliary power unit used to provide electrical power when theairplane is on the ground.

- No evidence has been found to indicate that theeight-cell, 32-volt battery was overcharged, the NTSB said.

- The safety board has not yet ruled out internal defects inthe battery, or problems with the associated equipment,including the charger, made by Securaplane, a unit of Britain'sMeggitt Plc, the NTSB said.

- Inspectors did find one issue in both the battery chargingunit and the starting power unit built by Securaplane, but it isnot yet clear what role those issues might have played in thebattery fire, the NTSB said.

REMAINING QUESTIONS:

- What are the similarities and differences between whathappened in Boston, where firefighters were called to extinguisha serious fire, and on the plane that landed in Japan?

- There were reports of smoke in the airliner that landed inJapan, but was there fire?

- Why did multiple systems fail that were designed toprevent a battery failure from getting out of control?

- Did the certification process for use of the highlyflammable lithium-ion batteries on board the 787 properly assessand understand the risks of fire?

OTHER PARTICIPANTS IN INVESTIGATION:

- Japan National Transportation Safety Board

- Japan Airlines

- U.S. Federal Aviation Administration

- Boeing

- Thales SA, the French company responsible forthe power conversion system on the plane.

- GS Yuasa Corp, the Japanese company that buildsthe lithium-ion batteries

- UTC Aerospace Systems, a unit of United Technologies Corp, which makes the auxiliary power unit and is the primarycontractor responsible for electrical systems on the 787

- U.S. Naval Surface Warfare Center, Carderock Division,which has been working on lithium-ion batteries since the 1970s